As an image forming apparatus for a printer, a facsimile machine, a copying apparatus, and a multifunctional machine having these functions, an inkjet recording apparatus is known which includes a liquid droplet ejecting apparatus using a liquid droplet ejecting head as a recording head, for example. The inkjet recording apparatus ejects a recording material (ink) from a liquid droplet ejecting head to a sheet (not limited to paper and includes an OHP sheet, etc., representing what a recording liquid such as ink, etc., and other liquids, etc., can be adhered to; also called a “medium to be recorded on”, or a “recording medium”, “recording paper”, etc.) to perform recording, making it possible to record a very fine color image at high speed. Moreover, the inkjet recording apparatus is also used in an industrial system such as a textile printing apparatus, etc.
Such a liquid droplet ejecting head for use in such an inkjet recording apparatus generally includes multiple nozzle sequences; and multiple dedicated liquid chambers (also called “pressure chambers”) which are communicatively connected to the nozzle sequence, to which multiple dedicated liquid chambers of a common recording material storage unit (also called “a common liquid chamber”) with a relatively large volume is communicatively connected. Energy may be selectively applied to the dedicated liquid chamber to deform the dedicated liquid chamber and cause liquid droplets to be ejected to form an arbitrary image on demand. As a medium for applying energy, a piezoelectric element, a heater chip, etc., are known.
Recently, there is a demand for an image forming apparatus to be able to output a higher definition image at a higher printing speed. In response to the demand for the higher definition image, there is a trend for an increased number of nozzles and a higher density. In conjunction thereto, there is a trend toward a narrower gap between respective dedicated liquid chambers and also a higher frequency of energy application. In response to the demand for the higher printing speed, there is an attempt to lengthen the recording head, and a so-called “line-type printer” is also proposed which includes the recording head which may cover the whole width region of the recording medium.
Energy applied to the dedicated liquid chamber causes a pressure variation in liquid droplets (recording material) within the dedicated liquid chamber, which pressure variation also spreads to a common liquid chamber to which it is communicatively connected and also influences, as a matter of course, a recording medium within a different neighboring dedicated liquid chamber (this is called “a mutual interference”).
There is a problem that the mutual interference induces unintended ejecting of liquid droplets or destabilizing of an ejection state, resulting in not being able to obtain a high definition image output.
A configuration provided with a damper is disclosed for preventing such a mutual interference (see Patent Documents 1 to 3, for example).
Patent Document 1 discloses an inkjet head which can prevent ink from penetrating into a damper chamber. In the inkjet head, a concave portion is provided by half etching at a position which opposes a portion at which a manifold continues from an opening, which position is on a face which is joined to a nozzle plate of a cover plate, which concave portion is sealed by the nozzle plate to form the damper chamber. It is disclosed therein that this damper chamber is for absorbing the pressure variation which is spread from the pressure chamber to the manifold, and grooves, which respectively extend from the damper chamber, formed on the cover plate, are formed and connect to a hole communicatively connected to the atmosphere.
Patent Document 2 discloses an inkjet head which is provided with a substrate which forms a common liquid chamber and a damper immediately below a substrate in which dedicated liquid chambers are formed. Patent Document 3 discloses a liquid ejecting head, wherein a buffer chamber is formed on the same plane as a dedicated liquid chamber forming portion.